Loading and Exploring Your Data

GVPT399F: Power, Politics, and Data

Data visualisation

We will use data visualization to answer the following question:

Do cars with big engines use more fuel than cars with small engines?

Load relevant packages

# Installing new packages
install.packages("ggthemes")

# Load the relevant packages
library(tidyverse)
library(ggthemes)

Loading in relevant data

# Load the data
mpg
manufacturer model displ year cyl
audi a4 1.8 1999 4
audi a4 1.8 1999 4
audi a4 2.0 2008 4
audi a4 2.0 2008 4
audi a4 2.8 1999 6
audi a4 2.8 1999 6

EXERCISE


Learn more about this data set by typing ?mpg into your console.

The mpg data set

glimpse(mpg)
Rows: 234
Columns: 11
$ manufacturer <chr> "audi", "audi", "audi", "audi", "audi", "audi", "audi", "…
$ model        <chr> "a4", "a4", "a4", "a4", "a4", "a4", "a4", "a4 quattro", "…
$ displ        <dbl> 1.8, 1.8, 2.0, 2.0, 2.8, 2.8, 3.1, 1.8, 1.8, 2.0, 2.0, 2.…
$ year         <int> 1999, 1999, 2008, 2008, 1999, 1999, 2008, 1999, 1999, 200…
$ cyl          <int> 4, 4, 4, 4, 6, 6, 6, 4, 4, 4, 4, 6, 6, 6, 6, 6, 6, 8, 8, …
$ trans        <chr> "auto(l5)", "manual(m5)", "manual(m6)", "auto(av)", "auto…
$ drv          <chr> "f", "f", "f", "f", "f", "f", "f", "4", "4", "4", "4", "4…
$ cty          <int> 18, 21, 20, 21, 16, 18, 18, 18, 16, 20, 19, 15, 17, 17, 1…
$ hwy          <int> 29, 29, 31, 30, 26, 26, 27, 26, 25, 28, 27, 25, 25, 25, 2…
$ fl           <chr> "p", "p", "p", "p", "p", "p", "p", "p", "p", "p", "p", "p…
$ class        <chr> "compact", "compact", "compact", "compact", "compact", "c…

The mpg data set

A couple of useful variables:

  • displ: engine displacement, in litres

  • hwy: highway miles per gallon

EXERCISE

  1. How many rows are in mpg? How many columns?
nrow(mpg)
ncol(mpg)


  1. What does the drv variable describe?
?mpg